Industrial products, such as automobiles, are often provided with a coating for the purpose of protection and aesthetic appearance. When the substrate to be coated is a plastic material, ultraviolet rays must be prevented from reaching the surface of the material to protect the material from degradation when outdoors. When the substrate is a metallic material, the material may be treated to have an aesthetic appearance after a coating film of an anticorrosion coating composition is formed from the standpoint of corrosion resistance. In the latter case as well, ultraviolet rays must be prevented from reaching the surface of the coating film formed of an anticorrosion coating composition.
Patent Literature 1 teaches that UV transmission is controlled in a method for producing a multilayer coating comprising the successive steps of applying an 8- to 20-μm thick coating layer from an aqueous coating composition A to a substrate provided with an EDC primer, applying a 5- to 15-μm thick base coat layer from an aqueous coating composition B to the previously applied coating layer, applying a clear coat layer to the base coat layer, and jointly curing the three coating layers. Patent Literature 1 discloses as a technique only that the coating compositions A and B are different from each other, and that the coating composition A contains at least one metal platelet pigment having a thickness from 10 to 100 nm in a proportion corresponding to a pigment/resin solids ratio by weight from 0.06:1 to 0.2:1. Thus, Patent Literature 1 cannot be applied to the full gamut of colors.